Technical Abstract:
There is a long tradition of integrated pest management (IPM) in the North Central region of the U.S. IPM is difficult to define, and it means different things to different people. But in general it is a philosophy based on multiple tactics to prevent a population from building up to unacceptable damaging levels. If preventive tactics are determined or projected to be inadequate, then a rescue tactic is applied. There are a number of constraints on adoption of IPM by growers. The growth in farm size has put a premium on efficiency, whereas IPM can demand extra effort and time on the part of the grower. The introduction of Bt corn and glyphosate-resistant crops have fit right in with a grower's desire to be more efficient, and in many respects these transgenic tools are highly compatible with IPM strategies. For example, Bt corn is often looked upon as a glorified form of host plant resistance, which is true in many respects. But there are also some differences when looked at in an IPM implementation context. The big issue confronting many North Central growers is that overuse of transgenic products has led to problems with weed and insect resistance in some key pests. To illustrate many of the issues involved, two contrasting case studies of insect pests of corn are presented. Area wide suppression of the European corn borer by lepidopteran active Bt corn has been a spectacular success story, and so far resistance has not developed despite continuing high selection pressure. In contrast, the other major insect pest of corn, the western corn rootworm, has developed field resistance to Cry3Bb1 Bt corn. Though not yet present in all areas of the North Central states, the problem seems to be spreading geographically. In response, many entomologists are calling for a return to IPM in an effort to manage the fallout, slow the spread, and prevent resistance developing in other traits or pyramids containing Cry3Bb1. But a common reaction so far has been to layer multiple chemical insecticide tactics on top of Bt traited corn. This "kitchen sink" approach is going to be a challenge to curtail, given the current high commodity price of corn and growers' heightened desire to protect yield.